MATTER

(Lat. materia*.) Substance. Of the innmate nature of matter the human faculties cannot take cognizance,nor can data be furnished, by observation or experiment,on which to found an investigation of it. All wo know, or ever can know of matter, is its sensible properties. Some of these are the foundation of physical science; others of the different subordinate sciences, as, for instance. Of chemistry. Matter is divisible by abrasion, and other means, into small fragments, which, when the division is carried to air. considerable extent, are called particles. It is supposed. however, and many reasons appear to justify the hypothesis, that it is capable of reduction into particles (called atoms) of particular tbrnis, and each cla having its own proper magnitude and peculiar properties; that determinate numbers of atoms of one kind admit of combination with some determinate Bomber of another kind, or of several kinds, and of thereby forming compounded atoms, having properties peculiar to that combination, and different from the known properties of their elemental atoms. These solutions and combinations result from properties inherent in the atoms themselves; but whether the simple cla es of atoms that tire believed to exist are themselves really primary and elemental is not known, and probably never can be with certainty. In larger ma es, or in ma es of aggregated atoms, so cla ed that their peculiar properties are mutually neutralized, phenomena are exhibited which bear a great resemblance to one another through considerable cla es of such Compound*, whose aleme we have reason to helieve differ very considerably; and other properties are found to exist in all, and dill'ering only in degree or intensity. These last are the (Object* of physical investigation: they are called emphatically the properties of matter; and the laws of their mutual influences ure the foundation of mechanical philosophy. These properties may be regarded as either e ential or contingent. The e ential properttee of matter are usually reckoned the following: 1. /' which every known substance po e es of being separable into parts, and these again into smaller parts, and so on until the parts become innppre ciable to our senses; nor can any limit be placed to the sub division. 2. Impenetrability, or a resistance exerted by every body to the occupation of its place by another. This resistance is of various degrees of intensity, dependent on the state and atomic composition of Hie bodies; but no two bodies can simultaneously occupy the same place. 3. Porosity, or the separation of the particles or atoms from each other by intervals or pores. Every substance with which we are acquainted is more or le porous 4. Compre ibility, or the property in virtue of which the volume of every body may be contracted into smaller dimensions. Among the e ential properties of matter may also be included extension and figure; but these belong also to space, and form the subject of geometry. The contingent properties of matter ore mobility and weight. Matter in every form is capable of being moved from one place to another; and every substance gravitates towards the centre of the earth. But motion has reference to space, and weight to the attraction of other matter. The above are the general properties of matter, upon which physical investigations depend. There are, however, vaiimis other qualities belonging to particular substances, or to matter in particular states, the consideration of which is important in mechanical philosophy. Among these the principal ore elasticity, fluidity, hardne , rigidity, solidity — for which see the respective terms. [s. 741]